1. Field of the Invention
The present invention relates to an apparatus for disintegrating calculuses of the type in which a calculus in a human body of a patient is disintegrated with a disintegrating energy of a shock wave externally applied.
2. Description of the Related Art
The calculus disintegrating apparatus using the disintegrating energy of a shock wave for disintegrating a calculus or calculuses in a human body have been developed as an apparatus for curing a disease by renal calculus or gallstone without surgical operations. In this type of apparatus, a shock wave is generated by making use of an electric spark or ultrasonic wave oscillation, and a calculus to be desintigrated in a human body is irradiated with the shock wave. To effectively irradiate the calculus with the shock wave, it is required that no air layer exists in a propagating path of the shock wave (i.e., between a shock wave generator and the body surface of a patient). The reason for this is that the air layer impedes propagation of the shock wave within the human body because, the wave is reflected by the air layer. This requirement may be readily satisfied by filling the propagation path with a liquid medium, e.g., water. There have been known two specific approaches to realize this. In a first method, a shock wave generator is placed in a bath tub filled with water. A patient is sunk into the bath tub. Under this condition, the shock wave is radiated toward the patient through the water. In a second method, an expandable container such as a rubber bag filled with the liquid is disposed in the front of a shock wave generator. The container is made to closely contact the body of a patient, before the shock wave is radiated. The shock wave generator and the container form an applicator. In the second method, a patient need not to sink into the bath tub. In this respect, mental and physical strain on a patient is lessened.
It is desirable that the applicator is disposed above a patient laid on the bed. The reason for this is that the direction of shock wave radiation may be readily checked, and that an operation of the applicator resembles that of a conventional medical apparatus, such as an X-ray apparatus and an ultrasound diagnostic apparatus, and therefore such a layout of the applicator above the patient allows an operator, e.g., a doctor, to be easily accessible to the applicator. With the layout of the applicator above the patient, when the applicator is positioned to focus the shock wave generator on the calculus, an operator may mistakenly move the applicator down to far, or supply an excessive amount of liquid medium into the applicator. Consequently, a patient is strongly pressed against the bed. In other words, where the position of the applicator and the amount of the liquid are both proper, the patient may be comfortably subjected to treatment, without any feeling of the weight of the applicator and the liquid. On the other hand, where the position of the applicator or amount of liquid is improper, the applicator strongly presses the patient against the bed. Under this condition, the patient feels uncomfortable, and in an extreme case, he has difficulty in breathing, and he may suffer a fracture due to excessive pressure.